I didn't say that. I said that while the exercise sequence in the video may give a good cardio workout, the strength/hypertrophy component is likely compromised; I didn't say it was nonexistent. I'm not saying it's a walk in the park, just that there are more efficient ways to build strength.
People use momentum to lift a weight that they could otherwise not be able to lift without momentum. Therefore, to make a momentum-type exercise sufficiently difficult to be worthwhile, you have to use a higher weight than you would use for an exercise that does not require momentum, all else being equal. A heavier weight with momentum is a riskier proposition than a lighter weight without momentum. That is my point. Plus, when not using momentum, the muscles are under tension for the entire range of motion rather than just a portion of it. The guy in the video was using momentum. It may look good and feel good. And you may prefer it. I don't.
Again, I'm not suggesting that what you are proposing is easy, and I'm not suggesting it has no value. But I don't think that working all of the muscle groups at the same time ("all muscles forced to fire at the same time") adequately and completely works any individual muscle group. You can't work all muscle groups to or near failure at the same time. I'm all for efficiency and focus almost exclusively on compounds. But I prefer one at a time. Consider a compound of your choice, be it a squat, a pull-up or whatever, and do it with absolutely no momentum at a deliberate and uniform speed both up and down to the point of failure. I think that is how you make maximal inroads.
I think compounds taken to failure can enhance athleticism, and certainly when coupled with cardio comprising bursts of max speed intervals.
"Mirror exercises" are mostly isolation-type exercises, which I have discarded years ago. Basic compounds have evolutionary relevance, whereas isolation exercises do not. As for narcissism, I could make that argument for swinging a heavier weight rather than properly lifting a lighter one and making the muscle work every inch of the way, both up and down.
While I don't fall for the evolution reference, I get what you are talking about in terms of functionality of the compound movement. And that's what I've been trying to describe, too. The oly lifts provide an incremental functionality benefit over squats alone that in my view are as large as the squat over a leg press. It's precisely this difference that I'm talking about.
And lets face it. Claiming that traditional weightlifting workouts in a gym are for the health/functionality benefits is like saying that we look at Playboy for the articles. It's bullshit. It's done to look good. And no, people don't do oly lifts to look good. The walls of traditional gyms are nothing but mirrors. The walls in a gym where they oly lift are not. There's a reason for that.
Hey, when you're right, you're right, and old Fred was right, least in my case.